TEHRAN, Young Journalists Club (YJC) - Xi's comments provoked a swift rebuke from Taipei, where President Tsai Ing-wen said Taiwan's people would never willingly give up the kind of democratic freedoms unseen on the mainland.
China still sees democratic Taiwan as part of its territory to be reunified, despite the two sides being ruled separately since the end of a civil war in 1949.
"China must and will be united... which is an inevitable requirement for the great rejuvenation of the Chinese people in the new era," Xi said in a speech commemorating the 40th anniversary of a message sent to Taiwan in 1979, in which Beijing called for unification and an end to military confrontation.
"We make no promise to give up the use of military force and reserve the option of taking all necessary means" against Taiwanese separatist activities and "outside forces" that interfere with reunification, he said.
In his speech, Xi described unification under a "one country, two systems" approach that would "safeguard the interests and well-being of Taiwanese compatriots".
Taiwan considers itself a sovereign state, with its own currency, political and judicial systems, but has never declared formal independence from the mainland.
Relations have been strained since the 2016 election of President Tsai, who has refused to acknowledge Beijing's stance that the island is part of "one China".
"Democratic values are cherished by the Taiwanese people, it's their way of life," Tsai told reporters in a press conference arranged in response to Xi's speech.
She also accused Beijing of provocations that strained people's "emotional connection" to the mainland such as "buying off" Taiwan's few diplomatic allies and increased military drills near the island.
Source: AFP